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Cold Conclusion to December

December 29, 2017

Cold Conclusion to December:

Cold weather dominated Minnesota and much of the nation for the last week of December. Minnesota reported the coldest temperature in the nation on 7 days during the month of December (so far). For the Twin Cities the week between Christmas Day and New Years Eve will be one of the coldest since 1886. On Christmas Day Wind Chill values at places like Orr, International Falls, and Warroad ranged from -40 to -45 degrees F. Both Kabetogama and Cotton set new record lows on December 28th with readings of -40°F and -42°F, respectively. International Falls reported a new record cold maximum temperature for December 26th with a reading of -12°F, while Embarrass and Pokegama Dam only "warmed up" to -18°F that day setting records for cold maximum temperatures. At International Falls a new record cold minimum for December 27th was set with a reading of -37°F. Even more cold temperature records may be reported over December 30-31 this weekend. Thankfully towards the end of the first week in January temperatures are expected to moderate back closer to normal values.

Preliminary Climate Summary for December:

Despite a near equal distribution of days with above normal and below normal temperatures, the month of December will end up colder than normal across the state, only the third month this year (along with May and August) with a mean monthly temperature that was cooler than normal. Most of the warmth came early in the month. Over the first four days of the month temperatures averaged 15 to 20 degrees F warmer than normal. During this time 19 new daily maximum temperature records and 12 new daily warm minimum temperature records were set within the state climate network. Conversely, the last week of the month, beginning with Christmas Day (25th) brought temperatures that ranged from 15 to 24 degrees F cooler than normal. In fact a few spots reported the coldest Christmas Day maximum temperature in their climate records, including -12°F at Park Rapids and -11°F at Hibbing and Ely. Over the period from December 25-28 at least 31 new record daily low minimum temperature records were set and over 40 new record cold daily maximum temperature records were set. Extremes for the month ranged from 61°F on the 4th at Minnesota City, Hastings, and Zumbrota to -42°F at Cotton on the 28th. Over 20 climate stations reported an extreme minimum temperature of -30 degrees F or colder.

Overall December precipitation was generally less than normal, with many places reporting less than half an inch. Snowfall was near normal in nothern parts of the state, typically ranging from 10 to 16 inches, while in the southern part of the state snowfall was less than normal. Portions of St Louis, Lake, and Cook counties in the northeast received over 19 inches for the month. Only the far northern counties had over 8 inches of snow depth.

Several days produced wind gusts over 30 mph, and on the 4th of the month a number of western climate stations reported wind gusts over 50 mph.

Looking Back at the Weather of 2017, Part Two:

Of all the months in 2017 February was the most anomalous. It was the 5th warmest February in state history (back to 1895). There were 285 new daily high maximum temperature records set and 148 new daily warm minimum temperature records set within the climate observer network. Minneapolis Crystal Airport hit 70 degrees F on February 19th, one of only a few times in Minnesota history that the thermometer has hit 70°F during the month of February.

The three tornadoes reported on March 6th (in Freeborn, Faribault, and Sherburne Counties) were the earliest on the calendar ever reported in Minnesota history. Fortunately they produced relatively modest damage.

June 11 brought one of the most damaging hail storms in years across portions of southern and central Minnesota. Many areas reported golf ball size hail stones.

The strongest convective thunderstorms of the year occurred over August 16-17 when Redwood Falls reported a new state record rainfall of 9.45 inches and 8 tornadoes were reported as well. Many climate stations reported rainfall amounts ranging from 3 to 6 inches with widespread street flooding.

It was an unusual growing season in terms of temperature pattern, showing below average number of days with 90 degrees F temperatures, and one of only nine years in Twin Cities history when there were no days in August with 90°F temperatures, but then they occurred a month later during September.

Of final note, the Minnesota State Climatology Office Facebook page is conducting a survey to vote on the top five Minnesota weather stories of 2017. If you wish to vote please go to the SCO Facebook page.

Weekly Weather Potpourri:

Continental snow cover maps are available from NOAA and can be viewed on-line for any calendar interval. Currently the snow cover across the continental USA is below normal for this time of year, with many states reporting below normal snow depths.

New research from the AGU suggests that algae growth on the Greenland ice sheet may be reducing its reflectivity significantly and affecting the rate of melting more than earlier thought. In fact, the algae growth on the ice may be contributing more to the melting that accumulation dust or black carbon.

While the Great Lakes Region has been experiencing colder than normal temperatures recently, Alaska has been recording an exceptionally warm month of December with daily temperatures averaging about 15 degrees F above normal. So far over 200 new daily maximum temperature records have been set this month within the Alaska climate network.

A recent study published in Geophysical Research Letters and highlighted by the AGU suggests that anthropogenic climate change may be impacting the frequency of summer droughts in the mid-latitudes.

MPR listener question:

This holiday season between Christmas Day and New Years Eve is the coldest I can remember in the Twin Cities. Has there ever been a year when the average temperature for this week was below zero degrees F in the Twin Cities?

Answer:

Indeed it appears that the week between Christmas Day and New Years Eve this year will deliver an average Twin Cities temperature that is below zero degrees F, perhaps on the order of -2 to -4 degrees F. This is rare territory in Twin Cities climate statistics. Only three years have brought temperature conditions that averaged below zero degrees F during the week between Christmas Day and New Years Eve in the Twin Cities. Those years were 1880 (-0.6°F), 1886 (-4.7°F), and 1924 (-1.8°F).

Twin Cities Almanac for December 29th:

The average MSP high temperature for this date is 24 degrees F (plus or minus 11 degrees F standard deviation), while the average low is 9 degrees F (plus or minus 13 degrees F standard deviation).

Average dew point for December 29th is 7°F; the maximum dew point on this date is 40°F in 1936; and the minimum dew point on this date is -24°F in 1976.

All-time state records for December 29th:

The all-time state high temperature for today's date is 61 degrees F at Montevideo (Chippewa County) in 1999; the all-time state low for today's date is -47 degrees F at Itasca State Park (Clearwater County) in 1917. The all-time state record precipitation for this date is 1.55 inches at Farmington (Dakota County) in 1982. Record snowfall is 16.0 inches also at Farmington (Dakota County) in 1982.

Past Weather Conditions:

Bitter cold dominated the state on December 29, 1887. Northern and western Minnesota communities reported temperatures ranging from -35 to -40 degrees F, while as far south as Rochester the temperature was -29°F. The daytime high temperature at Moorhead was only -11 degrees F.

The coldest December 29 in state history occurred in 1917. Morning low temperatures of -30 degrees F or colder were reported from 50 communities across the state. The temperature never rose above -18 degrees F at Ada (Norman County), making for one of the coldest days in history there.

A large winter storm brought heavy snowfall to parts of southwestern and central Minnesota over December 27-29, 1982. Snowfall amounts ranged from 8 to 18 inches and many roads were closed for a time.

December 29, 1999 was the warmest in state history. Over 30 communities reported an afternoon high temperature of 50 degrees F or greater. Redwood Falls and Milan reached 60 degrees F, while Montevideo set a state record for the date with 61 degrees F. Some western Minnesota citizens enjoyed an outdoor lunch.

Outlook:

Generally dry, clear, and cold over New Year’s Weekend, with temperatures from 15 to 20 degrees below normal. It may be the coldest New Year's Eve since 1992. Some moderation in temperature is seen by Tuesday and Wednesday with daytime highs in the single digits and teens. There will be a gradual warming to near normal temperatures by next weekend.